DESCRIPTION: The atrial natriuretic peptide is a cardiac hormone which plays an important role in regulation of cardiovascular and renal function. ANP is produced predominately in the cardiac atria while relatively small amounts are also found in the ventricule which can be activated to a very high level under certain developmental and pathophysiological conditions. The ANP gene is regulated by a variety of hormones and neuro transmitters including glucocorticoids, vitamin D, thyroid hormone and endothelin. The investigators propose to identify the regulatory factors which control expression of the ANP gene and decipher the mechanism underlying the negative regulation of this gene by the liganded vitamin D receptor. They will attempt to dissect the mechanism through which two regulatory elements, the AP-1 sensitive thyroid hormone responsive element (TRE) and the serum response element control ANP gene transcription. They will also attempt to develop a transcription system capable of initiating expression of ANP gene in vitro. Taken together these experiments should provide a definitive picture of the molecular controls which operate to govern tissue specific and regulated transcription of ANP gene.